Thursday, 27 July 2017

How, on current trends, peak demand for electricity is likely to fall in spite of rapid adoption of electric cars

Just as in 2005 the UK was rushed into an ill-judged nuclear programme by scare-stories of imminent power blackouts, we are now being herded into a panic mode by lop-sided projections of future energy demand out of fear of electric vehicles.

EVs are the future of motorised road transportation of course, and I'm sure it will happen quite quickly. But if you work out the figures based on past trends you find out that after re-working the National Grid's recent projections peak demand is actually likely to FALL, not increase.

There is always a supply-side bias in energy projections, and the numbers that are pouring out of the newspapers are the latest manifestation of this phenomenon.

One factor which almost everybody seems to have missed is that electricity demand has fallen since 2005 by around 12 per cent (in 2006 the Government talked about dramatic increases in demand). If you carry this forward to the future then this rate of decline would be more than the increase associated with the expansion in the number of EVs that was assumed by the National Grid in their most recent report. Given the fact that they identified opportunities for load shifting, in particular through 'time of use' charging that would reduce peak demand by up to 4.5 GW, that adds up altogether to a substantial FALL in the amount of peak generating capacity required in 2030.

In fact EVs supplied with electricity by sources such as wind, solar or marine energy are extremely efficient. First, the EVs themselves are, in terms of energy used to move a given distance much more energy efficient than conventional motor vehicles - and this difference is likely to increase as EVs mature as a technology. They have about a threefold advantage in energy efficiency. If the electricity is generated by these renewable energy sources then very little will be wasted (mainly grid losses) before the power is used in the vehicle. In fact the extra electricity needed to power the NG's projected expansion in EVs will be easily covered by the expansion in renewable energy if we assume recent trends continue.

Using the National Grid's assumption that around 9 million road vehicles constituting around one quarter of Britain's road transport fleet will be EVs by 2030 then some 108 TWh of petrol/diesel consumption will be replaced by around 40 TWh of electricity. Since 2012 renewable energy production has increased by over 40 TWh between 2012 and 2016.

There have been some ridiculously exaggerated numbers printed in one leading newspaper (I won't dignify them by mentioning their name) about the numbers of wind turbines needed to cover the extra production for EVs. In fact there are now around 7600 wind turbines in the UK. Given increasing sizes of offshore wind turbines (soon to be 10 MW each) and also increasing levels of efficiency for the newest models (with capacity factors approaching 50 per cent) then no more than 1000 new wind turbines would be needed to generate the demand for all of the EVs in operation by 2030. 

Now, for various reasons, including cutting carbon emissions and reducing our dependency on imported natural gas, we ought to be doing a lot more than that. Which, I suppose, if I were more cynical might lead me to forget about about countering the exaggerated stuff about the need for new power plant since this boosts the need for renewable energy. But getting further towards the objective of providing close to 100 per cent of our energy from renewables, as well as promoting energy efficiency, are good things in themselves and enough of an incentive to do a lot more than what we are doing now.

Some notes:

Nissan leaf 30 KWh per 100 miles

Average miles per gallon uk
38 mpg or 2.6 gallons per 100 miles

10 KWh per litre of petrol or 46 KWh per gallon or 2.6xs 46 KWh per 100 miles =120 KWh per 100 miles

Electricity from RE is at least 3xs as efficient as a petrol driven motor. Or 120 divided by 3.3 = 3.6xs as efficient.

37 mtoe used in road transport in 2016

11.63 MWh in1 tonne of oil. 11.63 TWh in 1 million tonnes of oil or 430 TWh from 37 mtoe divided by 3.6 comes to about 120 TWh.
A quarter of this is 40 TWh if approaching 50 cf is reached no more than 10 GW of capacity is needed. Already got 7.600 machines.

National grid report 9 million electric cars and vehicles in 2030 = 8GW of extra peak.

UK electricity demand has fallen from a peak of 406 TWh in 2005 to 357 TWh in 2016.
Renewable Energy Production has increased from 41 to 83 TWh from 2012 to 2016.

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